In the production of elongated elements by rolling, drawing, and similar operations, interstage annealing is often required which produces a more or less strong scaling or at least oxidation of the surfaces. Such scale layers must be removed before the further processing. Chemical methods may be used for this purpose but involve difficulties in connection with the disposal of the pickling agents which have been employed and which in most cases are liquid. For this reason, descaling by means of wire-grinding machines has been increasingly adopted because it involves less potential for pollution of the environment.
Unlike elements of short length, wires, rods, strip material and the like cannot be ground by fixing them, e.g. in a lathe, rotating them, and machining them with a stationary or also rotating grinding member to which an axial feed is imparted. Wires and the like must be axially advanced as they are ground and in that operation their three-dimensional relation to the grinding member must be controlled by guides. To provide for a descaling over the entire outer surface of the wire, care must also be taken to create relative rotation between the axially advancing wire and the grinding member.
According to one proposal, this is accomplished in an apparatus for grinding round stock which comprises a stationary supporting frame carrying a system or support which rotates about an axis that is parallel to the direction of travel of the stock to be ground, and at least two rotating wheels mounted on the rotating system.
In that apparatus the rotating grinding members are offset by 180.degree. from each other with respect to the axis of rotation of the system so that the stock to be machined is ground on two mutually opposite lines of contact at the same time. Such machining is possible only if guide means are provided to hold the stock to be machined in the correct position relative to the grinding members. Such guide means must be provided close to the point where grinding is performed so that it can take up the reaction forces which are due to the grinding operation. On the other hand, in apparatus comprising a pair of simultaneously operating grinding wheels the space which is available for such guide means is very small, particularly when it is desired to grind material which is relatively small in cross-section. In addition the adjustment for the grinding members relative to each other and to the guide means involves a considerable expenditure because economic grinding can be expected only if very exact adjustment is employed.